The manufacture of glass containers such as bottles, jars, and the like involves the shaping of the molten glass in a mold assembly, which consists of metallic components. The mold assembly is operated on an automatic machine they can produce glass bottles and jars at high production rates. Molten glass is dropped into a mold assembly at a temperature of about 1200 degrees Centigrade and is formed into a shape by the action of different components. Traditionally the mold is made of gray cast iron or bronze, and the internal components are made of a variety of steels, cast irons or nickel alloys.
The conditions inside glass container manufacturing apparatus are severe. There are frequent and severe temperature changes as the molten glass is introduced then ejected as a partly formed bottle in every machine cycle. Machine cycles can be a short as a few seconds. The components of the container manufacturing apparatus must be able to resist this thermal cycling without cracking.
It is an object of the invention to provide an alloy, having particular application to glass making apparatus such as molds and plungers for glass container manufacturing that can be made by standard melting and molding techniques used in ferrous foundry operations.
Another object of the invention is to provide an alloy that has a high hardness in the as cast condition and preferably as high as 55 Rockwell C.
Still another object of the invention is to provide an alloy that (a) can be heat treated to allow for machining operations to be carried out and (b) can re-hardened thereafter for service by standard normalizing and tempering procedures.
Yet another object of the invention is to provide glass making machinery components that have excellent service lives when employed as parts of glass bottle manufacturing apparatus and maintain sharp edges on surfaces in contact with molten glass longer than traditional materials.
Still another object invention is to provide apparatus that is capable of a substantial service life despite the severe and very frequent temperature cycling encountered within glass container manufacturing apparatus.
Is now been found that these and other objects of the invention may be attained in an alloy or an article of manufacture including but not limited to plunger and mold articles used in glass container manufacturing which consists of
(a) carbon 0.1 to 0.5% by weight;
(b) silicon 0 to 2% by weight;
(c) manganese 0 to 2% by weight;
(d) sulphur 0.02 to 0.05% by weight;
(e) phosphorus 0.02 to 0.05% by weight;
(f) nickel 0 to 3% by weight;
(g) chromium 5 to 35% by weight;
(h) molybdenum 0 to 5% by weight;
(i) copper 0 to 3% by weight;
(j) boron 0.5 to 3.5% preferably 1.8 to 2.2%
(h) The balance of the composition is iron.
In some embodiments of the invention the component (i) copper is in the range 0.2 to 1% by weight; the component (a) carbon is in the range 0.2 to 0.3% by weight; the component (b) silicon is in the range 0.5 to 1.5% by weight and the component (c) manganese is in the range 0.4 to 1.5% of weight.
The component (f) nickel may be in the range 1.0 to 1.5% by weight; the component (g) chromium may be in the range 15 to 20% by weight; and the component (h) molybdenum is in the range 0.1 to 0.3% by weight. The component (j) boron may be in the range 1.8 to 2.2% by weight.